Bariatric sleeve

ABSTRACT

Method and apparatus for limiting absorption of food products in specific parts of the digestive system is presented. A gastrointestinal implant device is anchored in the stomach and extends beyond the ligament of Treitz. All food exiting the stomach is funneled through the device. The gastrointestinal device includes an anchor for anchoring the device to the stomach and a flexible sleeve to limit absorption of nutrients in the duodenum. The anchor is collapsible for endoscopic delivery and removal.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.10/339,786, filed on Jan. 9, 2003, now U.S. Pat. No. 7,025,791 whichclaims the Provisional Application Ser. No. 60/430,321, filed Dec. 2,2002. The entire teachings of the above applications are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

According to the Center for Disease Control (CDC), over sixty percent ofthe United States population is overweight, and almost twenty percentare obese. This translates into 38.8 million adults in the United Stateswith a Body Mass Index (BMI) of 30 or above. The BMI is defined as aperson's weight (in kilograms) divided by height (in meters), squared.To be considered clinically, morbidly obese, one must meet one of threecriteria: BMI over 35,100 lbs. overweight or 100% above ideal bodyweight. There is also a category for the super-obese for those weighingover 350 lbs.

Obesity is an overwhelming health problem. Because of the enormousstrain associated with carrying this excess weight, organs are affected,as are the nervous and circulatory systems. In 2000, the NationalInstitute of Diabetes, Digestive and Kidney Diseases (NIDDK) estimatedthat there were 280,000 deaths directly related to obesity. The NIDDKfurther estimated that the direct cost of healthcare in the USassociated with obesity is $51 billion. In addition, Americans spend $33billion per year on weight loss products. In spite of this economic costand consumer commitment, the prevalence of obesity continues to rise atalarming rates. From 1991 to 2000, obesity in the US grew by 61%. Notexclusively a US problem, worldwide obesity ranges are also increasingdramatically.

One of the principle costs to the healthcare system stems from theco-morbidities associated with obesity. Type-2 diabetes has climbed to7.3% of the population. Of those persons with Type-2 diabetes, almosthalf are clinically obese, and two thirds are approaching obese. Otherco-morbidities include hypertension, coronary artery disease,hypercholesteremia, sleep apnea and pulmonary hypertension.

Although the physiology and psychology of obesity are complex, themedical consensus is that the cause is quite simple—an over intake ofcalories combined with a reduction in energy expenditures seen in modemsociety. While the treatment seems quite intuitive, the institution of acure is a complex issue that has so far vexed the best efforts ofmedical science. Dieting is not an adequate long-term solution for mostpeople. Once an individual has slipped past the BMI of 30, significantchanges in lifestyle are the only solution.

There have been many attempts in the past to surgically modify patients'anatomies to attack the consumption problem by reducing the desire toeat. Stomach saplings, or gastroplasties, to reduce the volumetric sizeof the stomach, therein achieving faster satiety, were performed in the1980's and early 1990's. Although able to achieve early weight loss,sustained reduction was not obtained. The reasons are not all known, butare believed related to several factors. One of which is that thestomach stretches over time increasing volume while psychologicaldrivers motivate patients to find creative approaches to literally eataround the smaller pouch.

There are currently two surgical procedures that successfully producelong-term weight loss; the Roux-en-Y gastric bypass and thebiliopancreatic diversion with duodenal switch (BPD). Both proceduresreduce the size of the stomach plus shorten the effective-length ofintestine available for nutrient absorption. Reduction of the stomachsize reduces stomach capacity and the ability of the patient to take infood. Bypassing the duodenum makes it more difficult to digest fats,high sugar and carbohydrate rich foods. One objective of the surgery isto provide feedback to the patient by producing a dumping syndrome ifthey do eat these food products. Dumping occurs when carbohydratesdirectly enter the jejunum without being first conditioned in theduodenum. The result is that a large quantity of fluid is dischargedinto the food from the intestinal lining. The total effect makes thepatient feel light-headed and results in severe diarrhea. For reasonsthat have not been determined the procedure also has an immediatetherapeutic effect on diabetes.

Although the physiology seems simple, the exact mechanism of action inthese procedures is not understood. Current theory is that negativefeedback is provided from both regurgitation into the esophagus anddumping when large volumes of the wrong foods are eaten. Eventually,patients learn that to avoid both these issues they must be compliantwith the dietary restrictions imposed by their modified anatomy. In theBPD procedure, large lengths of jejunum are bypassed resulting inmalabsorption and therefore, reduced caloric uptake. In fact, thestomach is not reduced in size as much in the BPD procedure so that thepatient is able to consume sufficient quantities of food to compensatefor the reduced absorption. This procedure is reserved for the mostmorbidly obese as there are several serious side effects of prolongedmalabsorption.

Unfortunately, these procedures carry a heavy toll. The morbidity ratefor surgical procedures is alarmingly high with 11% requiring surgicalintervention for correction. Early small bowel obstruction occurs at arate of between 2-6% in these surgeries and mortality rates are reportedto be approximately 0.5-1.5%. While surgery seems to be an effectiveanswer, the current invasive procedures are not acceptable with thesecomplication rates. Laparoscopic techniques applied to these surgeriesprovide fewer surgical complications but continue to expose these veryill patients to high operative risk in addition to requiring an enormouslevel of skill by the surgeon. Devices to reduce absorption in the smallintestines have been proposed (See U.S. Pat. No. 5,820,584 (Crabb), U.S.Pat. No. 5,306,300 (Berry) and U.S. Pat. No. 4,315,509 (Smit)). However,these devices have not been successfully implemented.

SUMMARY OF THE INVENTION

A gastrointestinal implant device includes a flexible sleeve and asleeve anchor, which may be a stent including a network of struts,coupled to a proximal portion of the sleeve. The flexible sleeve is openat both ends, and adapted to extend into the duodenum to limitabsorption of nutrients in the duodenum. The sleeve anchor is adapted tobe retained within the digestive system. For example, the device may beanchored distal to the pylorus, leaving the pylorus to functionnormally, or a stent may be retained within the pyloric orifice to holdthe pylorus open.

The sleeve anchor is collapsible allowing the implant device to beremoved. A stent may be covered by a proximal portion of the sleeve andsandwiched between a first inner layer and a second outer layer of thesleeve. The sleeve may be of a length that chyme exiting the stomachfunneled through the proximal end of the sleeve exits the sleeve throughthe distal end below the ligament of Treitz. The sleeve material mayhave a coefficient of friction of less than 0.2. The sleeve may beformed of low friction materials such as expandedpolytetrafluoroethylene, a fluoropolymer, or low density polyethylenefilm and may be coated or impregnated with polyurethane or silicone toreduce permeability. The sleeve is generally flexible and can be thinand floppy. The distal end of the sleeve may be directionally textured.

The device may be anchored using barbs, sutures, and/or other anchordevices. For example, barbs extend from the exterior surface of thestent for anchoring the proximal portion of the sleeve to muscle. Thebarbs may be bidirectional. The barbs anchor the flexible sleeve to thepyloric muscle in the stomach.

An anti-buckling device may be coupled to the sleeve and extend frombelow the stent to the distal end of the flexible sleeve to reducetwisting and buckling of the sleeve. The sleeve allows enzymes secretedin the duodenum to pass through the duodenum outside the sleeve.

The gastrointestinal implant device can be inserted endoscopically incombination with a delivery catheter and can be removed endoscopicallyin combination with a removal device.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

FIG. 1 is a sectional view of a portion of the digestive tract in abody;

FIG. 2 is a perspective view of a gastrointestinal implant deviceaccording to the principles of the present invention;

FIG. 3A is a plan view of the proximal portion of the gastrointestinalimplant device shown in FIG. 2;

FIG. 3B is a cross-sectional view as taken along line A-A of FIG. 3Ashowing the stent and first inner layer and second outer layer of thesleeve shown in FIG. 2;

FIG. 4 is a perspective view of the gastrointestinal implant device withthe second outer layer of the sleeve removed;

FIG. 5A is a sectional view of a body showing one embodiment of thegastrointestinal implant device implanted in the digestive system;

FIG. 5B is a sectional view of a body showing an alternative embodimentof the gastrointestinal implant device implanted in the digestivesystem;

FIG. 6 is a perspective view of a collapsible self-expanding stent inthe gastrointestinal implant device;

FIG. 7 is a perspective view of the stent shown in FIG. 6 whencompressed;

FIG. 8 is a perspective view of another embodiment of a stent whencompressed;

FIG. 9 is a perspective view of the stent shown in FIG. 8 with the strutends bent to provide opposed barbs;

FIG. 10 is a perspective view of the stent shown in FIG. 8 whenexpanded;

FIG. 11 illustrates the gastrointestinal device shown in FIG. 1including an anti-buckling mechanism;

FIG. 12 is a perspective view of a catheter system for delivery of thegastrointestinal implant device;

FIG. 13 is a cross-sectional view of the inner shaft taken along lineE-E of FIG. 12;

FIG. 14A is an expanded perspective view of the dead-bolt mechanismshown in FIG. 12;

FIG. 14B is a sectional view of the dead-bolt mechanism shown in FIG.13A illustrating the sleeve retention wire threaded through the sleeve;

FIG. 15 is sectional view of a portion of the catheter systemillustrating the collapsed stent stored inside the outer sheath;

FIG. 16A is a plan view of the catheter system illustrating thecollapsed stent stored inside the outer sheath of the gastrointestinalimplant device;

FIG. 16B is a plan view of the catheter system illustrating thegastrointestinal implant device after release of the stent from theouter sheath;

FIG. 16C is a plan view of the catheter system illustrating the expandedgastrointestinal implant device after the sleeve retention wire has beenreleased;

FIG. 17 is a perspective view of another embodiment of the cathetersystem shown in FIG. 12;

FIG. 18 is a sectional view of an everting catheter system for deliveryof a longer length sleeve;

FIG. 19 is a perspective view of a retrieval device for removing thegastrointestinal implant device from the digestive tract;

FIG. 20 is a perspective view of the removal device engaged with thestent;

FIG. 21 is a perspective view of another embodiment of agastrointestinal implant device;

FIG. 22 is a perspective view of the anchoring ring shown in FIG. 21;

FIG. 23 is a perspective view of the anchoring ring shown in FIG. 21 ina collapsed position for insertion and removal;

FIG. 24 is a perspective view of an anchor for anchoring the collapsiblering shown in FIG. 23 to the muscular tissue of the pyloric section ofthe stomach;

FIG. 25A is a perspective view of a delivery system for delivering theanchor after the gastrointestinal implant device has been placed in thestomach;

FIG. 25B is a plan view of the delivery system shown in FIG. 25A;

FIG. 25C is a cross-sectional view of the distal end of the catheter astaken along line B-B of FIG. 25A;

FIG. 25D is a perspective view of the gastrointestinal implant deviceillustrating the anchor engaged with the tissue;

FIG. 25E is a perspective view illustrating the barb engaging the tissueafter delivery;

FIG. 26A is a plan view of the delivery system including a snare wirefor holding the distal end of the sleeve in position;

FIG. 26B is a cross-sectional view taken along line CC of FIG. 26Athrough the inner sheath;

FIG. 26C is a cross-sectional view taken along line DD of FIG. 26Athrough the outer sheath showing the inner sheath within the outersheath;

FIG. 26D is a cross-sectional view through the distal portion of thecatheter showing the snare capturing the distal end of the sleeve;

FIG. 26E is a sectional view through the distal portion of the cathetershowing the snare locking mechanism; and

FIG. 27 is a perspective view of the distal portion of thegastrointestinal implant device including texturing at the distal end.

DETAILED DESCRIPTION OF THE INVENTION

A description of preferred embodiments of the invention follows.

FIG. 1 is a sectional view of a portion of the digestive tract in abody. Food to be digested enters the stomach 102 through the cardiacorifice 110 from the esophagus. Chyme, a semi-fluid, homogeneous creamyor gruel-like material produced by gastric digestion in the stomachexits the stomach through the pyloric orifice (pylorus) 108 and entersthe small intestine 112. The pylorus 108 is a distal aperture of thestomach 102 surrounded by a strong band of circular muscle. The smallintestine, about nine feet in length, is a convoluted tube, extendingfrom the pylorus to the ileo-caecal valve where it terminates in thelarge intestine. The small intestine has three sections, the duodenum104, jejunum 106 and the ileum (not shown). The first eight to ten inchsection of the small intestine, the duodenum, is the shortest, widestand most fixed part of the small intestine.

The duodenum has four sections: superior, descending, transverse andascending which typically form a U-shape. The superior section is abouttwo inches long and ends at the neck of the gall bladder. The descendingsection is about three to four inches long and includes a nipple shapedstructure (papilla of vater) 114 through which pancreatic juice from thepancreas and bile produced by the liver and stored by the gall bladderenter the duodenum from the pancreatic duct. The pancreatic juicecontains enzymes essential to protein digestion and bile dissolves theproducts of fat digestion. The ascending section is about two incheslong and forms the duodenal-jejunal flexure 116 where it joins thejejunum 106, the next section of the small intestine. Theduodenal-jejunal flexure 116 is fixed to the ligament of Treitz 118(musculus supensionus duodeni). The juices secreted in the duodenumbreak the partially digested food down into particles small enough to beabsorbed by the body. The digestive system is described in Gray'sAnatomy (“Anatomy of the Human Body”, by Henry Gray) and “HumanPhysiology”, Vander, 3^(rd) ed, McGraw Hill, 1980, the contents of whichare incorporated herein by reference in their entirety.

FIG. 2 is a perspective view of a gastrointestinal implant device 200according to the principles of the present invention. Thegastrointestinal implant device 200 includes an elongated open-endedflexible sleeve or tube 202 having a first proximal opening 204 and asecond distal opening 206. Within the sleeve 202 is a passageway thatextends from the first proximal opening 204 to the second distal opening206 for transporting the chyme exiting the stomach 102 (FIG. 1). Thesurface of the passageway (the interior surface of the implant device200) is smooth to enable the chyme to easily pass through. The exteriorsurface of the implant device 200 is smooth to prevent tissue in-growthand to be non-irritating to the bowel.

Within the implant device 200 at the proximal end including the firstproximal opening 204 is a collapsible self-expanding stent 208. Thestent 208 includes a plurality of opposed barbs 210 for anchoring theimplant device 200 to the muscular pylorus in the stomach 102. Thediameter of the stent 208 is dependent on the diameter of the pyloricorifice 108 (FIG. 1) about 0.8″ to 1.1″ based on human anatomyvariations. In one embodiment, the length l of the stent 208 is selectedto extend through the pylorus 108 and keep the pylorus 108 permanentlyopen to induce “dumping syndrome.” In an alternate embodiment, a stentwith a shorter length l allows the pylorus 108 to open and closenormally.

The sleeve material is thin and conformable so that it collapses in theintestine to a small volume to minimize bowel irritability. It has a lowcoefficient of friction (<0.20) so that chyme slides easily through itand the bowel slides easily around it. It is of low permeability tofluids so that the chyme does not touch the bowel wall and the digestiveenzymes do not significantly breakdown the chyme. It is biologicallyinert and non-irritating to the tissues. One such material is expandedpolytetrafluoroethylene (ePTFE), a fluoropolymer, with a wall thicknessof about 0.006″ and an internodal distance of 20 microns. This materialis hydrophobic but is slightly porous. However, these very small poresmay plug over time. The porosity may be reduced by coating the materialon the inside, outside or in the pores with dilute solutions of siliconeor polyurethane. Another material is polyethylene with a wall thicknessof less than 0.001″. Rubber-like materials typically have frictioncoefficients of 1-4, significantly stickier than these materials.However, in alternate embodiments other materials having similarcharacteristics can be used.

The sleeve 202 includes two layers of material at least at the proximalend. A first outer layer covers the exterior of the stent. The secondinner layer covers the interior surface of the stent 208. The barbs 210protrude from the exterior surface of the stent 208 through the firstouter layer of the sleeve 208. The holes in the first outer layerthrough which the barbs 210 protrude are filled with an imperviousmaterial such as silicone or urethane to limit mixing of digestivejuices with the chyme flowing through the passageway. The diameter ofthe sleeve 208 is selected such that the first outer layer of the sleeve208 fits over the stent 208.

The sleeve length 212 ranges from about one foot to about five feet. Thetypical length of the sleeve 208 is about 1.5 feet from the anchor(barbs 210) in the pyloric region of the stomach to below the ligamentof Treitz 118 (FIG. 1). The length 212 of the sleeve 202 is selected tobypass the duodenum 104 (FIG. 1) and a portion of the jejunum. Thelength is increased to further decrease absorption by bypassing a longersection of the jejunum 106 (FIG. 1). The length 212 of the sleeve 202 isvariable and dependent on the patient's Body Mass Index (BMI). Theprocedure is a less invasive alternative to surgery for the treatment ofobesity and morbid obesity and also provides a new treatment approachfor type 2 diabetes.

The covered stent 208 can be collapsed into a sheath having a diameterless than ¼ inch to enable endoscopic delivery. Covering the exteriorsurface of the stent 208 with the first outer layer of the sleeve 202permits endoscopic removal of the implant device 200 by preventingtissue in-growth on the exterior surface of the stent 208.

Markings can be added to the exterior surface of the sleeve 202 todetect the position and orientation of the sleeve on a fluoroscopicimage and whether the sleeve is twisted. For example, a stripe can bepainted down the length of the device 200 using tantalum impregnatedink, or tantalum bands can be bonded to the exterior surface of thedevice. If the sleeve 202 is twisted, the sleeve 202 can be untwisted byinserting a balloon into the proximal end of the device thereby sealingit, and then injecting water into the sleeve at low pressure.

FIG. 3A is a plan view of the proximal portion of the gastrointestinalimplant device shown in FIG. 2. FIG. 3B is a cross-sectional view astaken along line AA of FIG. 3A showing the stent 208 and the first outerlayer 300 and the second inner layer 302 of the sleeve 202 shown in FIG.2. As described in conjunction with FIG. 2, the sleeve 202 includes afirst outer layer 300 and a second inner layer 302. The first outerlayer 300 is bonded to the second inner layer 300 at positions 306 belowthe distal end of the stent 208 and at positions 308, above the proximalend of the stent 208. A passageway 304 inside the second inner layer 302of the sleeve 202 allows passage of chyme through the sleeve 202. Thestent 208 is sandwiched between the first outer layer 300 and the secondinner layer 302 at the proximal end of the sleeve 202 and is free tomove at the distal end within the first outer layer 300 and the secondinner layer 302 of the sleeve 202. The covered exterior surface of thestent 208 prevents tissue growth to allow removal of the implant device200. The covered interior surface of the stent 208 provides a smoothpassageway for chyme to bypass the duodenum 104.

FIG. 4 is a perspective view of the gastrointestinal implant device 200with the first outer layer 300 of the sleeve 202 removed. Theinterconnecting struts which form the mesh (a network of struts) withdiamond spaced openings are sufficiently flexible to allow the stent tobe collapsed inside a delivery catheter and have sufficient elasticityto hold the pylorus open once the catheter is withdrawn. The forceneeded to hold the pylorus open is about 1-2 lbs. of radial forceoutward when the stent is compressed from its full diameter by 25%.

FIG. 5A is a sectional view of a body showing one embodiment of thegastrointestinal implant device 200 implanted in the digestive system.The first proximal end 204 of the implant device 200 is anchored tomuscle in the pyloric portion of the stomach 102. The barbs 210 griponto the muscle to anchor the implant device 200 in place so that theimplant device 200 can not be dragged into the stomach or down into theintestines with movement of the stomach and the intestines. FIG. 5B is asectional view of a body showing an alternative embodiment of thegastrointestinal implant device 200′ implanted distal to the pylorus108.

The sleeve 202 extends over the ligament of Treitz 118 beyond theproximal jejunum. Extending the sleeve below the ligament of Treitzreduces the likelihood that the sleeve will move back through theduodenum 104 toward the stomach 102.

After the gastrointestinal implant device 200 has been placed in thebody and anchored in either the pyloric portion of the stomach or distalto the pylorus 108, chyme leaving the stomach passes through passageway304 (FIG. 3B) inside the sleeve 202 and bypasses the duodenum 104 andproximal jejunum 106. By directing the chyme through the sleeve 202 thedigestion and the absorption process in the duodenum 104 is interrupted.By interrupting mixing of the chyme with juices in the duodenum 104,partially digested food material is not broken down into particles smallenough to be absorbed by the body. Further, there is no mixing of bilewith the chyme until the chyme reaches the jejunum 106. The absorptionof fats and carbohydrates is reduced by delaying the mixing of bile withthe chyme.

The pyloric valve opens periodically to allow chyme to exit the stomach102 to the duodenum 104. In one embodiment of the invention the lengthof the stent 208 is selected to keep the pyloric valve permanently opento induce “dumping syndrome.” By keeping the pylorus 108 open, the chymeempties rapidly into the sleeve 202 and passes down through the sleeve202 and into the jejunum 106 with minimal digestion. This results in a“dumping syndrome” which is a reaction to excessive rapid dumping ofchyme into the jejunum 106 causing the patient to feel ill, dizzy andnauseated. This syndrome is particularly enhanced when sugars andcarbohydrates are eaten and passed directly into the jejunum 106.

To hold the pyloric valve open, the length of the stent 208 should be atleast 1.5 inches so that the stent 208 extends from the anchoringposition in the pyloric portion of the stomach through the pyloricorifice 108 (the opening from the stomach while the pyloric valve isopen). The length of the stent is selected so that the distal end of thestent is above the papilla of vater 114 (FIG. 1). As shown, the stent208 extends through the pyloric orifice 108 to hold the pyloric valvepermanently open. In an alternative embodiment, the length of the stent208 is selected such that the stent 208 ends at the stomach side of thepyloric orifice 108 allowing the pyloric valve to operate normally.

The sleeve 202 provides weight loss mechanisms by providing negativefeedback, reduced fat digestion and reduced desire for food. The reducedfat digestion occurs because the sleeve 202 delays the mixing of bileand pancreatic juices with chyme from the stomach until after the chymeleaves the sleeve. The reduced desire for food may occur because thesleeve 202 blocks hormonal release from the duodenum.

After the chyme from the stomach has passed through the sleeve, thesleeve becomes extremely thin and floppy, permitting the sleeve tocontour to the inner walls of the intestine. The sleeve is non-compliantand drapes away from the intestinal walls thereby permitting thepancreatic juice to flow unimpeded into the duodenum through the papillaof vater. The normal peristalsis of the bowel is used to propel thechyme through the intestines.

FIG. 6 is a perspective view of a collapsible self-expanding stent 600in the gastrointestinal implant device 200 shown in FIG. 2 whenexpanded. The stent 600 is non-woven, collapsible and self-expanding,allowing endoscopic insertion and removal of the implant device 200. Thestent 600 includes a plurality of flat struts 602 forming an open spacepattern to ease collapsing while ensuring self-expansion. The open spacepattern allows for collapsing into a catheter for endoscopic deliveryand removal. The struts 602 may be manufactured from heat-treated springsteel such as Nitinol or MP35N.

In the embodiment shown, the stent has a length L of about 1.5 inchesand has a diameter D of about 1 inch. The struts 602 are flat, about0.010 inches wide and about 0.004 to 0.010 inches thick. The stent canbe formed from a tube of material by laser cutting followed by expansionand heat setting, or other methods well known to those skilled in theart.

In an alternate embodiment, the struts 602 can be formed separately andthe strut intersections can be welded or attached by other means wellknown to those skilled in the art. Visually the struts form sections 604around the circumference of the stent. Each section has a series oftriangles with each triangle defined by one distal strut connection 606and two proximal strut connections 608, 610. The ratio of the collapseddiameter to the expanded diameter of the stent is roughly 1:4.

When expanded, the angle a between divergent strut sections is about45-50 degrees and the diameter of the stent is about one inch. Whencompressed, the angle β between divergent strut sections is about 5-6degrees to reduce the diameter of the stent to about 0.21 inch forendoscopic delivery and removal. The elasticity of the struts permitsthis compression. When the radial compression is released, theelasticity of the struts causes the stent to expand to diameter D. Thestent assumes its desired diameter as the elastic restoring forces seektheir minimum stress.

The ends of the struts at the proximal end of the stent 600 areelongated and shaped to provide barbs 612 to anchor to the muscle in thepyloric portion of the stomach 102.

FIG. 7 is a perspective view of the stent 600 shown in FIG. 6 whencompressed. The stent 600 is compressed until the angle β betweendivergent strut sections is about 5-6 degrees to reduce the diameter Dof the stent 600 to about 0.21 inch for endoscopic delivery and removal.The barbs 704 at the proximal end of the stent are elongated. The barbs704 can be shaped to anchor the stent to the muscular pylorus.

FIG. 8 is a perspective view of another embodiment of a stent 800 whencompressed. Pairs of barbs 802 at the proximal end of the stent 800 areelongated and can be shaped to provide opposed barbs to anchor the stent800 in the muscle of the pylorus.

FIG. 9 is a perspective view of the compressed stent 800 shown in FIG. 8with the strut ends 902, 900 bent to provide opposed barbs 904, 906. Thebarbs 904,906 engage the muscle of the pylorus to anchor thegastrointestinal implant device in the pylorus portion of the stomach.As shown in FIG. 2, the strut ends 900, 902 protrude outward from theouter surface of the stent 800 in opposite directions. They may beperpendicular to each other. The barbs 904, 906 at the ends of therespective opposed strut ends 900, 902 dig into the pylorus muscle toanchor the stent. The barbs 904, 906 at the end of the protrudingopposed strut ends 900, 902 prevent movement of the stent 800 in eitherdirection; that is, they prevent movement of the stent 800 into thestomach and prevent movement of the stent 800 down through the duodenum.

FIG. 10 is a perspective view of the stent 800 shown in FIG. 8 whenexpanded. As discussed in conjunction with FIG. 9, the barbs 904, 906engage the muscle of the pylorus while the stent 800 is expanded. In theengaged position, the barbs 904, 906 spread radially outward from thelongitudinal axis of the stent 800 such that the tips of the barbs comeinto contact and engage the tissue.

FIG. 11 illustrates the gastrointestinal device 1100 shown in FIG. 1including an anti-buckling mechanism 1102. A flexible, anti-rotation,anti-buckling mechanism 1102 is attached to the sleeve 202 and extendsfrom below the distal end of the stent along the length L of the sleeveto the distal end of the sleeve 202. In the embodiment shown, theanti-buckling mechanism 1102 is a guidewire device attached to theexterior surface of the outer layer of the flexible sleeve. Guidewiredevices are well known to those skilled in the art. A first proximal endof the guidewire device 1104 is attached below the stent and a seconddistal end of the guidewire device 1106 is attached to the distal end ofthe flexible sleeve. The diameter of the guidewire ranges from about0.010″ to about 0.016″.

The length of the sleeve 202 can be sized to just pass over the ligamentof Treitz thereby bypassing only the duodenum and proximal jejunum 106.By doing this, it may not be necessary to provide any anti-bucklingmechanisms in the sleeve 202 since the duodenum 104 is not very mobilecompared to the jejunum 106. Typically, an anti-buckling mechanism 1102is added to the exterior surface of a sleeve 202 having a lengthexceeding the length of the duodenum 104 and proximal jejunum 106.

The gastrointestinal implant device 200 is designed for endoscopicplacement. FIG. 12 is a perspective view of a portion of a cathetersystem 1200 for delivery of the gastrointestinal implant device. Thecatheter system follows a guide wire 1212 through the esophagus and thestomach to the pylorus portion of the stomach. The guide wire 1212enters a first inner lumen at the proximal end 1208 of the cathetersystem 1200 and exits the first inner lumen at the distal end 1222 ofthe catheter system 1200.

The catheter system 1200 includes an outer sheath 1202 for storing thestent 208 in collapsed form, a flange 1216 to pull back the outer sheath1202 and a sleeve retention wire mechanism 1214 for releasing a sleeveretention wire 1210 from the proximal end of the flexible sleeve 202after the stent has been released from the outer sheath 1202.

As described in conjunction with FIG. 2, the distal portion of thegastrointestinal implant device includes a flexible sleeve 202 which cannegotiate the duodenum and the jejunum. A sleeve retention wire 1210travels through a second inner lumen and exits the second inner lumen tosecure the distal end of the sleeve 202 to an inner sheath 1226. Thesleeve retention wire 1210 is coupled to the sleeve retention wirerelease mechanism 1214 for releasing the sleeve retention wire 1210after the gastrointestinal implant device has been positioned in thepyloric section of the stomach. The release mechanism 1214 will bedescribed later in conjunction with FIG. 16B.

The sleeve 202 is secured temporarily outside the inner sheath 1226allowing for proper positioning of the gastrointestinal implant deviceand then for release. As shown, the sleeve 202 is secured by the sleeveretention wire 1210 using a dead-bolt mechanism 1206. Non-stick coatingssuch as Teflon on the sleeve retention wire 1210 are preferred to makerelease easier to accommodate tortuous anatomical pathways. The sleeveretention wire 1210 extends through the second inner lumen from therelease mechanism 1214 of the catheter system 1200 to the dead-boltmechanism 1206. The dead-bolt mechanism 1206 is described later inconjunction with FIG. 13A. The sleeve retention wire 1210 holds thesleeve in position. The distal end of the folded sleeve is released bythe release mechanism 1214 by pulling the sleeve retention wire 1210backward from the proximal end 1208 of the catheter.

As described in conjunction with FIG. 1, the proximal portion of thegastrointestinal device includes a covered stent. The covered stent doesnot enter the duodenum and thus is stiffer than the sleeve because itremains in the pylorus of the stomach. The stent in the gastrointestinalimplant device is collapsed and stored in the outer lumen within theouter sheath 1202 between the flange 1216 and the distal end of theouter sheath 1202. The stent is supported in a collapsed form by theouter sheath 1202. The catheter 1200 is inserted into the digestivesystem through the esophagus to the pyloric section of the stomach. Theproximal end of the outer sheath 1202 is positioned in the stomach, inthe pylorus through the use of positioning ring 1224. After the outersheath 1202 has been positioned, the stent is retracted from the outerlumen of the catheter by pulling flange 1216 toward the proximal end ofthe catheter system 1200. Upon release, the stent self-expands by itsown elastic restoring force to engage the anchor portion with thestomach muscle at the pyloric section of the stomach.

FIG. 13 is a cross-sectional view of the inner shaft 1226 taken alongline E-E of FIG. 12. The sleeve retention wire 1210 passes through asecond inner lumen 1314 in the inner sheath 1226. The sleeve retentionwire 1210 exits the second inner lumen 1314 and is threaded throughfolds of the sleeve 202 at 1302 in FIG. 14A. The sleeve retention wire1210 re-enters the second inner lumen 1314 at 1302 (FIG. 14A). Theguidewire 1212 passes through the first inner lumen 1310.

FIG. 14A is an expanded perspective view of the dead-bolt mechanism 1206shown in FIG. 12. The sleeve 202 has been folded for delivery. Thesleeve is wrapped around the inner sheath 1226 and bunched above theinner sheath 1226 The sleeve is held in folded position around the innersheath 1226 by threading the sleeve retention wire 1210 through thefolds of the sleeve 202. The sleeve retention wire 1210 exits the secondinner lumen 1314 through an opening 1306 and pierces through folds ofthe sleeve 202 at 1304. Threading the sleeve retention wire 1210 throughthe folds of the sleeve 202 results in a plurality of small holes at thedistal end of the sleeve 202. The holes are reinforced with silicone orurethane to avoid tears in the material. The sleeve retention wire 1210re-enters the second inner lumen through a second hole 1302 and advancesa sufficient distance within the second inner lumen toward the distalend of the second inner lumen to resist pulling out of the second innerlumen.

FIG. 14B is a sectional view of the dead-bolt mechanism 1206 shown inFIG. 14A illustrating the sleeve retention wire 1210 threaded throughthe sleeve. The sleeve retention wire 1210 exits the second inner lumen1314 at 1306 and pierces through folds in the sleeve 202 at 1304. Thesleeve retention wire 1210 re-enters the second inner lumen 1314 at1302.

FIG. 15 is a sectional view of a portion of the catheter system shown inFIG. 12 illustrating the collapsed stent 208 stored inside the outersheath 1202. The stent 208 is pre-compressed and held in a collapsedform inside the outer sheath 1202 of the catheter. The outer sheath 1202is pulled back by the flange 1216 toward the proximal end of thecatheter system 1200 to release the self-expanding stent 208. The stentradially expands under its own elastic restoring force. The guidewire1212 is directed through the first inner lumen 1310 and the sleeveretention wire 1210 is directed through the second inner lumen in theinner sheath 1226. The inner sheath includes a first lumen through whichthe guidewire passes and a second lumen through which the sleeveretention wire passes.

FIGS. 16A-C illustrate a method for delivery of the gastrointestinalimplant device. FIG. 16A is a plan view of the catheter systemillustrating the collapsed stent stored inside the outer sheath 1202 ofthe gastrointestinal implant device. As described in conjunction withFIG. 12, the stent 208 is stored inside the outer sheath and the distalend of the sleeve 202 is secured outside the inner sheath 1226 by asleeve retention wire 1210.

FIG. 16B is a plan view of the catheter system 1200 illustrating thegastrointestinal implant device after release of the stent 208 from theouter sheath 1202. The flange 1216 has been pulled back toward theproximal end of the catheter system 1200 to pull back the outer sheath1202 from the stent and the stent 208 has self-expanded. The sleeveretention wire 1210 holds the distal end of the sleeve 202.

Once in place, the sleeve retention wire 1210 can be removed. Asdescribed previously in conjunction with FIG. 12, the sleeve retentionwire 1210 is coupled to locking mechanism 1224. Handle 1600 in thelocking mechanism 1214 acts as a pivot device to pull the sleeveretention wire 1210 from the dead-bolt mechanism 1206. The distal end ofthe gastrointestinal implant device is released by moving handle 1600 ina clockwise direction 1604. As the handle 1600 is moved in direction1604, the sleeve retention wire 1210 threaded through the folds of thesleeve is pulled back through the second inner lumen 1314 and disengagesfrom the sleeve at the distal end of the gastrointestinal implantdevice. The sleeve retention wire 1210 extends from the distal end ofthe gastrointestinal implant device through the second inner lumen 1314.The wire is connected to the handle 1600 at the proximal end of thecatheter.

FIG. 16C is a plan view of the catheter system illustrating the expandedgastrointestinal implant device after the sleeve retention wire has beenreleased. The handle 1600 has been moved in a clockwise direction andthe sleeve retention wire 1210 has been pulled back through the secondinner lumen 1314 to release the distal end of the sleeve 202.

FIG. 17 is a perspective view of another embodiment of the cathetersystem shown in FIG. 16. The catheter includes a ball 1800 coupled tothe distal end 1222 of the inner sheath 1226 for guiding the catheterthrough the alimentary canal (e.g., to the pyloric portion of thestomach). The ball 1800 is small enough so that it can be pulled backthrough the gastrointestinal implant device after the gastrointestinaldevice has been delivered, the stent expanded and the sleeve retentionwire 1210 has been released. The sleeve is shown uniformly folded 1204.However, the sleeve may not necessarily be uniformly folded.

FIG. 18 is a cross-section of an everting catheter system 1900 fordelivery of a longer flexible sleeve. The gastrointestinal implantdevice 200 is shown with the stent sleeve anchor 1901 and the attachedsleeve 1902 shown as delivered into the anatomy. The delivery catheterpreviously described is then removed. A balloon catheter 1906 isintroduced into the stent sleeve anchor 1901 and the balloon 1908inflated to seal the lumen of the stent 1901. The sleeve 1902 is foldedinside itself and an elastic band 1912 is used to seal the end of thesleeve. Fluid is then injected through the balloon catheter shaft 1906into the sleeve lumen 1910, filling the lumen and pressurizing it. Thepressure of the fluid is used to push the inner sleeve distally towards1904. When the sleeve 1902 has fully deployed distally, the elastic band1912 falls off of the closed end of the sleeve 1902 and passes distallyin the intestine until it is excreted. This mechanism permits deploymentof a sleeve that is double the length of the delivered device. This maybe needed as it is difficult to access the distal parts of the intestinewith guidewires. This everting catheter system enables delivery oflonger sleeves than are possible using only the delivery catheterdescribed in conjunction with FIG. 12.

FIG. 19 is a perspective view of a retrieval device 2000 for removingthe gastrointestinal implant device 200 from the digestive tract. Asalready described, the exterior surface of the stent 208 is covered witha material that prevents cellular in-growth allowing the stent 208 to beeasily removed. The retrieval device 2000 includes an inner sheath 2004and an outer sheath 2006. A plurality of fingers 2002 extend from theproximal end of the inner sheath 2004. The fingers 2002 engage theexterior surface of the gastrointestinal device. As the inner sheath2004 is moved down over the fingers, the fingers 2002 pull radiallyinward to reduce the proximal stent diameter and pull the collapseddevice into the outer sheath 2006.

FIG. 20 is a perspective view of the retrieval device 2000 engaged withthe stent 208. The fingers 2002 of the retrieval device are positionedaround the stent 208. As the inner sheath 2004 is pushed over thefingers 2002, the fingers pull radially inward on the proximal end ofthe stent 208 and the proximal end of the stent 208 is collapsed. Afterthe stent 208 has been collapsed sufficiently such that the proximalstent diameter is less than the diameter of the outer sheath 2006, thestent is drawn into the outer sheath 2006. The entire gastrointestinalimplant device can then easily be removed from the patient by pullingretrieval device 2000 through the stomach and the esophagus.

FIG. 21 is a perspective view of another embodiment of agastrointestinal implant device 2200. The gastrointestinal implantdevice 2200 includes a sleeve 202 and an anchoring ring 2204. The distalend of the anchoring ring 2204 is bonded to the proximal end of thesleeve 202. A plurality of eyelets 2206 are distributed around thecircumference of the proximal end of the ring for anchoring the deviceto the pyloric muscle using anchors shown in FIG. 24. The anchoring ring2204 is made from a flexible material such as silicone allowing the ring2204 to be collapsed for endoscopic insertion and removal.

The anchoring ring 2204 does not hold the pylorus open. However, in analternate embodiment, the anchoring ring 2204 can be bonded to a stentwith sufficient length and diameter to hold the pylorus open asdescribed in conjunction with FIG. 2. The anchoring ring 2204 anchorsthe device and the stent holds the pylorus open.

FIG. 22 is a perspective view of the anchoring ring 2204 shown in FIG.21 in the expanded position. The sleeve is bonded to the outer surface2300 of the proximal end of the anchoring ring whose diameter is 0.8″ orabout the same as the diameter of the sleeve. The anchoring ring 2204includes at least four eyelets to anchor the device in place. The outermost diameter of the ring is about one inch. In an alternate embodimentthere can be more than four eyelets.

FIG. 23 is a perspective view of the anchoring ring 2204 shown in FIG.21 in a collapsed position for insertion and removal. The circular ring2204 shown in FIG. 21 has been compressed to an oval shape allowing theanchoring ring to be inserted into the lumen of a catheter for delivery.

FIG. 24 is a perspective view of an anchor 2500 for anchoring thecollapsible ring shown in FIG. 23 to the muscular tissue of the pyloricorifice. The anchor 2500 includes an anchor pin 2504 coupled to a secondpin 2506 by a flexible shaft 2502. The anchor pin 2504 includes a shapedbarb 2508 for locking the anchor 2500 into the tissue. The anchor 2500is delivered after the collapsible ring has been positioned in thepyloric orifice. The anchor is guided so that the anchor pin 2504 isdirected through a respective eyelet with the barbed portion of theanchor pin 2504 guided toward the tissue. After the barb 2508 has beenlocked into the tissue, the second pin 2506 sits inside thegastrointestinal implant device while the barbed portion 2508 of theanchor pin 2504 sits inside the pylorus muscle tissue. For removal ofthe gastrointestinal implant device from the body, the flexible shaft2502 of the anchor 2500 is cut.

FIG. 25A is a perspective view of a delivery system 2600 for deliveringthe anchor 2500 after the gastrointestinal implant device has beenplaced in the pyloric orifice. The anchor 2500 is loaded in the distalend of a catheter having a single lumen tube 2600. The hollow, distalend of the delivery device is a sharp needle made to penetrate thepylorus muscle. In an alternate embodiment, the distal end of thedelivery device can be formed in an arc to improve access to the eyelets2206 through an endoscopic approach. The catheter 2600 includes a pusher2604 for releasing the anchor 2500. The pusher 2604 is moved in alongitudinal direction 2602 to release the anchor 2500 from the lumen.

FIG. 25B is a plan view of the delivery system 2600 shown in FIG. 25A.FIG. 25C is a cross-sectional view of the distal end of the catheter2600 as taken along line B-B of FIG. 25B. As described in conjunctionwith FIG. 24, the anchor 2500 includes pins 2504, 2506 coupled by aflexible shaft 2502. The anchor 2500 is loaded in the lumen at thedistal end of the catheter 2600. The anchor pin 2504 is placed in thedistal end of the tube 2600 and the second pin 2506 in the proximal end.The barb 2508 on the anchor pin 2504 is pointed toward the proximal endof the tube 2506 to engage with the tissue upon release in the muscletissue. The catheter is advanced to the center of the ring positioned inthe pyloric orifice. The sharp end 2510 is then pushed through an eyeletand into the muscle tissue. The pusher 2506 is pushed in longitudinaldirection 2602 to release the distal anchor 2506. Once the distal anchoris released, the delivery system is pulled back, dragging the proximalpart of the anchor out of the delivery device with the flexible shaftgoing through the eyelet, and the proximal anchor portion resting on theinside of the device. In the embodiment of the ring shown in FIG. 22,four anchors 2506 are delivered to anchor the gastrointestinal implantdevice through the four eyelets.

FIG. 25D is a perspective view illustrating the sharp end 2510 of theneedle inserted through an eyelet 2206 for delivery of the anchor 2500to the tissue 2512. The distal end of the catheter is formed in an arc2520 to improve access the eyelets 2206. The sharp end 2510 of thecatheter is inserted through the eyelet 2206 into the tissue 2516. Theanchor pin 2504 of the anchor has been pushed out from the lumen intothe tissue 2512.

FIG. 25E is a perspective view illustrating the barb 2508 engaging thetissue 2512 after delivery. The catheter has been removed from theeyelet 2206 leaving the anchor pin 2504 engaging the tissue 2512.

FIGS. 26A-E illustrate an alternative embodiment of a locking mechanismfor holding the distal end of the sleeve 202 in position during deliveryof the gastrointestinal implant device. A snare wire 2656 is passedthrough one of the lumens of a catheter 2650 to the distal end. At thedistal end, the end of the snare wire 2650 is looped back and attachedto or anchored inside the catheter 2650. The folds of the sleeve 202 areadvanced through this snare loop. The snare handle 2664 pulls andreleases the snare wire 2656 to lock and release the distal end of thesleeve 202. The delivery system includes a pull tap 2666 for releasing adrawstring holding the stent in a collapsed position.

FIG. 26B is cross-sectional view taken along line C-C of FIG. 26Athrough the inner sheath 2650. The inner sheath has two lumens 2654,2662 and has a diameter of about 0.078 inches. The first inner lumen2564 is for passing a guidewire through the inner sheath and is about0.04 inches in diameter. The second inner lumen 2662 is for passing thesnare wire through the inner sheath and is about 0.02 inches indiameter. The end of the snare wire 2658 is anchored inside the innersheath 2650.

FIG. 26C is a cross-sectional view taken along line DD of FIG. 26Athrough the outer sheath 2600 showing the inner sheath 2650 within theouter sheath 2600. The outer sheath has a inner diameter of about 0.1inches and an outer diameter of about 0.143 inches. The open spaceinside the outer sheath can be used for passing a drawstring through theouter sheath.

FIG. 26D is a cross-sectional view through the distal portion of thecatheter 2650 showing the snare capturing the distal end of the sleeve202. The distal end of the sleeve 202 is captured by the snare wire 2656by pulling the distal end of the sleeve through a loop formed by thesnare wire 2656.

FIG. 26E is a sectional view through the distal portion of the cathetershowing the snare locking mechanism. The distal end of the sleeve islocked by pulling the snare wire 2656 in a longitudinal direction 2664toward the proximal end of the delivery system to capture the sleevefolds against the inner shaft. After the gastrointestinal implant deviceis properly positioned in the body, the snare wire is advanced in alongitudinal direction 2662 toward the distal end of the deliverysystem. This opens the snare wire 2656 and releases the sleeve 202.

FIG. 27 is a perspective view of the distal portion of thegastrointestinal implant device including texturing 2700. Texturing ofthe distal end of the sleeve can be added to ensure that the actions ofperistalsis do not advance the sleeve proximally, towards the stomach,but keep the sleeve pulled taught in the intestine. At the distal end ofthe sleeve, texturing 2700 is added with a directional aspect to it. Thetexturing 2700 can be molded into the sleeve material or added byadhesive or thermal bonding methods. The texturing material containsincludes fibril shapes that are directed proximally so that anyperistaltic waves that travel proximally, will have less force on thesleeve than distal peristaltic waves.

The gastrointestinal implant device offers a new alternative where othermeans of weight loss and efforts at behavior modification have failed.Because the gastrointestinal implant device is endoscopicallyintroduced, there is a reduced risk at insertion compared to surgery.The procedure is also completely reversible, making this approach theideal solution for patients who are desperate to reverse behavioralpatterns that have lead to weight gain.

When inserted in the body, the gastrointestinal implant device mimicsthe duodenal bypass of the Roux-en-Y procedure. The implanted devicereduces caloric absorption by delaying enzyme mixing with food andprovides the feedback produced by the Roux-en-Y procedure by producingdumping syndrome when high sugar meals are ingested. Rapid stomachemptying is encouraged by inserting a stent in the pylorus to hold thepylorus open and all food bypasses the duodenum and passes rapidly intothe jejunum. The implant device is an improvement on the Roux-en-Yprocedure because it is minimally invasive and reversible. In thetreatment of the super-obese where aggressive weight loss is notachieved, the length of the implant device below the stent can befurther increased to drive the patient close to the point ofmalabsorption.

The gastrointestinal implant device can be used to reduce Type 2diabetes symptoms by bypassing the duodenum. Following gastric bypasssurgery, patients commonly experience complete reversal of Type 2diabetes. While the exact mechanism of this remarkable effect is notunderstood, the clinical result is reported in a high percentage ofcases. Reversal of Type 2 diabetes after gastric bypass is described in“Potential of Surgery for Curing Type 2 Diabetes Mellitus” by Rubino etal. incorporated herein by reference in its entirety. Since thegastrointestinal implant device provides equivalent blockage of duodenalprocesses, a similar effect is elicited but without the trauma ofsurgery. In patients who are not obese but suffer Type 2 diabetes, amodified gastrointestinal implant device is inserted. Thisgastrointestinal implant device provides the necessary effect to hinderpancreatic processes and receptors without blocking absorption.

In the embodiment of the gastrointestinal implant device for treatingdiabetes, the length of the stent is selected to allow the pylorus tooperate normally. The length of the sleeve is also reduced to mimic theduodenum bypass. The sleeve extends to just below the ligament of Treitzbut does not extend further into the jejunum, thus allowing absorptionto occur in the jejunum.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. A gastrointestinal implant device comprising: a flexible, floppysleeve, open at both ends, the sleeve being at least twelve inches inlength to extend within the intestine, the sleeve being thin andconformable so that it collapses in the intestine to a small volume; aself expanding stent, comprising a network of struts, coupled to aproximal portion of the sleeve, the stent being sized to anchor thesleeve at or distal to the pylorus in the digestive system, the sleevebeing unsupported at a distal end, the sleeve including two layers ofmaterial at least at the proximal end, a first outer layer covering theexterior surface of the stent and a second inner layer covering theinterior surface of the stent; and members coupled to the stent, themembers being structured and arranged to penetrate muscle, the membersbeing barbs extending from an exterior surface of the stent.
 2. Thegastrointestinal implant device of claim 1, wherein the stent is sizedto be retained distal to the pylorus.
 3. The gastrointestinal implantdevice of claim 1, wherein the stent is sized to be retained within thepyloric orifice.
 4. The gastrointestinal implant device of claim 1,wherein the stent is collapsible.
 5. The gastrointestinal implant deviceof claim 1, wherein the sleeve is of a length that chyme exiting thestomach funneled through the proximal end of the sleeve exits the sleevethrough the distal end below the ligament of Treitz.
 6. Thegastrointestinal implant device of claim 1, wherein the sleeve materialhas a coefficient of friction of less than 0.2.
 7. The gastrointestinalimplant device of claim 1, wherein the sleeve is formed of afluoropolymer.
 8. The gastrointestinal implant device of claim 7,wherein the fluoropolymer is expanded polytetrafluoroethylene.
 9. Thegastrointestinal implant device of claim 8, wherein the sleeve is coatedwith a coat of silicone.
 10. The gastrointestinal implant device ofclaim 8, wherein the sleeve is coated with a coat of polyurethane. 11.The gastrointestinal implant device of claim 1, wherein the sleeve isformed of polyethylene.
 12. The gastrointestinal implant device of claim1, wherein the distal end of the sleeve is directionally textured. 13.The gastrointestinal implant device of claim 1, wherein the barbscomprise pairs of barbs that are directed outwardly and in opposite,axial directions.
 14. The gastrointestinal implant device of claim 13,wherein the barbs are sized to anchor the flexible sleeve to the pyloricmuscle in the stomach.
 15. The implant device of claim 13, wherein thepairs of barbs are at a proximal end of the stent.
 16. Thegastrointestinal implant device of claim 1, further comprising ananti-buckling device coupled to the sleeve to reduce buckling of thesleeve.
 17. The gastrointestinal implant device of claim 16, wherein theanti-buckling device extends from below the stent to the distal end ofthe flexible sleeve.
 18. The gastrointestinal implant device of claim16, wherein the anti-buckling device reduces twisting of the sleeve. 19.The gastrointestinal implant device of claim 1, wherein the sleevecauses enzymes secreted in the duodenum to pass through the duodenumoutside the sleeve.
 20. The gastrointestinal implant device of claim 1in combination with a catheter to insert the flexible sleeve.
 21. Thegastrointestinal implant device of claim 1 in combination with a removaldevice to remove the flexible sleeve.
 22. A gastrointestinal implantdevice comprising: a flexible, floppy sleeve, open at both ends, thesleeve being at least twelve inches in length to extend within theintestine, the sleeve being thin and conformable so that it collapses inthe intestine to a small volume; and a self expanding and collapsiblesleeve anchor coupled to a proximal end of the sleeve, the sleeve anchorcomprising barbs extending from the exterior surface of the anchor andstructured, directed, and arranged for insertion into muscle as thesleeve anchor expands to anchor the proximal portion of the sleeve at ordistal to the pylorus, the sleeve being unsupported at a distal end, andthe sleeve including two layers of material at least at the proximalend, a first outer layer covering the exterior surface of the anchor anda second inner layer covering the interior surface of the anchor. 23.The gastrointestinal implant of claim 22, wherein the sleeve anchor is astent.
 24. The gastrointestinal implant device of claim 22, wherein thesleeve anchor is sized to be retained distal to the pylorus.
 25. Thegastrointestinal implant device of claim 22, wherein the sleeve anchoris sized to be retained within the pyloric orifice.
 26. Thegastrointestinal implant device of claim 22, wherein the sleeve is of alength that chyme exiting the stomach funneled through the proximal endof the sleeve exits the sleeve through the distal end below the ligamentof Treitz.
 27. The gastrointestinal implant device of claim 22, whereinthe sleeve material has a coefficient of friction of less than 0.2. 28.The gastrointestinal implant device of claim 22, wherein the sleeve isformed of a fluoropolymer.
 29. The gastrointestinal implant device ofclaim 28, wherein the fluoropolymer is expanded polytetrafluoroethylene.30. The gastrointestinal implant device of claim 29, wherein the sleeveis coated with a coat of silicone.
 31. The gastrointestinal implantdevice of claim 29, wherein the sleeve is coated with a coat ofpolyurethane.
 32. The gastrointestinal implant device of claim 22,wherein the sleeve is formed of polyethylene.
 33. The gastrointestinalimplant device of claim 22, wherein the distal end of the sleeve isdirectionally textured.
 34. The gastrointestinal implant device of claim22, wherein the barbs comprise pairs of barbs that are directedoutwardly and in opposite, axial directions.
 35. The implant device ofclaim 34, wherein the pairs of barbs are at a proximal end of theanchor.
 36. The gastrointestinal implant device of claim 22, wherein thebarbs are sized to anchor the flexible sleeve to the pyloric muscle inthe stomach.
 37. The gastrointestinal implant device of claim 36,wherein the anti-buckling device reduces twisting of the sleeve.
 38. Thegastrointestinal implant device of claim 22, further comprising ananti-buckling device coupled to the sleeve to reduce buckling of thesleeve.
 39. The gastrointestinal implant device of claim 38, wherein theanti-buckling device extends from below the anchor to the distal end ofthe flexible sleeve.
 40. The gastrointestinal implant device of claim22, wherein the sleeve causes enzymes secreted in the duodenum to passthrough the duodenum outside the sleeve.
 41. The gastrointestinalimplant device of claim 22 in combination with a catheter to insert theflexible sleeve.
 42. The gastrointestinal implant device of claim 22 incombination with a removal device to remove the flexible sleeve.
 43. Thegastrointestinal implant device of claim 22, wherein the collapsiblesleeve anchor is sized to be implanted distal to the pylorus.
 44. Thegastrointestinal implant device of claim 22, wherein the stent is sizedfor anchoring within the stomach.
 45. A gastrointestinal implant devicecomprising: a collapsible, floppy sleeve, the sleeve being at leasttwelve inches in length, and open at both ends to extend within theintestine, the sleeve being thin and conformable so that it collapses inthe intestine to a small volume; a self-expanding stent, comprising anetwork of struts, coupled to a proximal portion of the sleeve, thestent being sized to retain the sleeve at or distal to the pylorus inthe digestive system, the sleeve being unsupported at a distal end, andthe sleeve including two layers of material at least at the proximalend, a first outer layer covering the exterior surface of the stent anda second inner layer covering the interior surface of the stent; andmembers coupled to the stent, the members being barbs and extending fromthe exterior surface of the stent, the members being structured andarranged to penetrate muscle.
 46. The gastrointestinal implant device ofclaim 45, wherein the sleeve is formed of a fluoropolymer.
 47. Thegastrointestinal implant device of claim 45, wherein the sleeve is sizedto be retained distal to the pylorus.
 48. A gastrointestinal implantdevice comprising: a flexible, floppy sleeve, open at both ends, thesleeve being at least twelve inches in length to extend within theintestine, the sleeve being unsupported at a distal end, and the sleevebeing formed of expanded polytetrafluoroethylene, the sleeve being thinand conformable so that it collapses in the intestine to a small volume;a stent, comprising a network of struts, coupled to a proximal portionof the sleeve to anchor the sleeve distal to the pylorus, the sleeveincluding two layers of material at least at the proximal end, a firstouter layer covering the exterior surface of the stent and a secondinner layer covering the interior surface of the stent; and barbsextending from the exterior surface of the stent and sized to anchor aproximal portion of the sleeve to muscle in the digestive system.
 49. Agastrointestinal implant device comprising: sleeve means for extendingwithin the intestine, the sleeve means comprising a flexible, floppysleeve open at both ends and at least twelve inches in length, thesleeve being thin and conformable so that it collapses in the intestineto a small volume; and anchoring means for anchoring a proximal end ofthe sleeve, the anchoring means being collapsible and self-expanding andcomprising barb means on the exterior surface of the stent means forinsertion into muscle as the anchoring means expands to anchor theproximal portion of the sleeve, the sleeve being unsupported at a distalend, and the sleeve including two layers of material at least at theproximal end, a first outer layer covering the exterior surface of theanchoring means and a second inner layer covering the interior surfaceof the anchoring means.
 50. A gastrointestinal implant devicecomprising: sleeve means for extending within the intestine, the sleevemeans comprising a flexible, floppy sleeve open at both ends, the sleevebeing at least twelve inches in length, the sleeve being unsupported ata distal end, and the sleeve being formed of expandedpolytetrafluoroethylene, the sleeve being thin and conformable so thatit collapses in the intestine to a small volume; and anchoring means foranchoring the sleeve distal to the pylorus comprising a network ofstruts and coupled to a proximal portion of the sleeve, the anchoringmeans being self-expanding, the anchoring means comprising barb meansfor anchoring a proximal portion of the sleeve to muscle, the barb meansextending from the exterior of the struts, and the sleeve including twolayers of material at least at the proximal end, a first outer layercovering the exterior surface of the anchoring means and a second innerlayer covering the interior surface of the anchoring means.